Kinematics of an actuating mechanism for a telescoping antenna

In this work the position, velocity and acceleration analyses of a four-degrees-of-freedom serial manipulator are approached mainly by means of the theory of screws. Closed-form solutions are easily obtained for the displacement analysis of the mechanism owing the decoupled action of the generalized coordinates, while the input-output equations of velocity and acceleration of the manipulator are systematically obtained by means of the theory of screws. A case study is included with the purpose to exemplify the application of the method.En este trabajo los análisis de posición, velocidad y aceleración de un manipulador serial de cuatro grados de libertad se abordan principalmente por medio de la teoría de tornillos. El análisis de posición es resuelto en forma cerrada debido a la acción desacoplada de las coordenadas generalizadas mientras que las ecuaciones entrada salida de velocidad y aceleración del manipulador son obtenidas sistemáticamente por medio de la teoría de tornillos. Con el propósito de ejemplificar el método se proporciona un caso de estudio

Sensor based line follower self-driving car (sCar) with Obstacles Avoidance

This paper introduces the sensor based line follower Self-driving Car (sCar) with obstacles avoidance. We develop a Collision Avoidance path-planning Algorithm (CAA) for dual motors controller line follower sCar that has ability for navigate collision avoidance path autonomously through a constraint track from initial position to goal position. A sensor will be mounted in front of the sCar that will detect line and obstacles along the track. A powerful close loop control system is used in the sCar which can calcules collision free path. The sCar senses a line and endeavors a collision free path itself accordingly towards the initial position to desired goal position using a simple feedback mechanism but yet very effective closed loop system. In some situation, there will be multiple destinations and the sCar should able to choose the desired destinations based on CAA applied to the microcontroller Arduino UNO which acts as the center control unit. The CAA will be implemented by C++ programming language. Evaluation results show that CAA calculates collision free path with constant performance which independent on environments

Costos Logísticos y gestión aduanera en una agencia de Carga y Aduanas, en el Callao, periodo 2016 – 2020

La presente investigación se realizó con el objetivo de Determinar la relación que existe entre los costos logísticos y la gestión aduanera, en la Agencia de Cargas y Aduanas en el Callao, período 2016- 2020; investigación de enfoque cuantitativo, de tipo aplicada, de diseño no experimental de corte transversal, de nivel correlacional, que tuvo como población de base de datos de Infoescomar, Sunat y Trade Map , tipo de muestreo no probabilístico por conveniencia, aplicando la técnica de recolección de datos. Finalmente, se obtuvo el resultado de una relación de 0.06 entre las variables costos logísticos y gestión aduanera al presentar una correlación positiva ymoderada con un P valor igual a 0,920 que es mayor a 0.05 luego de aplicar el estadístico Rho Spearman. Concluyendo: que existe una relación de 6%

Nuevas narrativas para remotos y venerables artefactos: La colección profesor Gastón Soublette y el Aula de arte “Nuestros pueblos originarios”

Durante el año 2015, Gastón Soublette, músico, filósofo y profesor del Instituto de Estética, donó a la Universidad Católica su valiosa colección de objetos precolombinos y mapuches antiguos. Su propósito era instalar una exhibición en el Campus Oriente de la Pontificia Universidad Católica de Chile, para entregar una visión indígena del arte. Bajo el mandato de la Dirección de Infraestructura y Desarrollo Físico, curadores y diseñadores trabajaron para desarrollar un guion de contenido y montaje que recogiera estas inquietudes. En particular, la belleza y las creencias depositadas en estas obras del pasado americano

Digital materials to strength learning process in upper secondary education: A study to understand how educational change takes place

Se presenta un estudio en el marco de un proceso de cambio educativo en relación con la técnica Aula Invertida con apoyo de la herramienta de aprendizaje Living Class (LC) para apoyar el estudio de las disciplinas de química y ciencias sociales en educación media superior. El proceso de cambio se define a partir de dos aportaciones teóricas que integran cinco pasos: iniciación, planeación, implantación, evaluación e institucionalización. Se realizaron tres sub-estudios para indagar a profundidad el proceso de cambio que se suscitaba en la institución: uno sobre usabilidad de la herramienta LC y dos sobre percepción alrededor del proceso de cambio y apoyo en la herramienta, los cuales se enfocaron en colectar la percepción de docentes y estudiantes respectivamente. Participaron en total 4,708 estudiantes y 154 docentes. El estudio se enmarcó en el diseño metodológico de Métodos mixtos. Las conclusiones conllevaron a afirmar que el proceso de cambio educativo se encuentra en la fase de implantación. La discusión apunta a diagnosticar el estadio en el que se encuentra un proceso de cambio educativa de forma holística. Se realizan sugerencias para estudios futurosThis article presents the results of a study made in order to analyze a process of educational change in upper secondary level. It focused on the implementation of Flipped Classroom technique supported by a learning tool called Living Class (LC). The educational change phenomena is defined within this study from two theoretical contributions that build a five steps process: initiation, planning, implementation, evaluation and institutionalization. Three sub-studies were conducted to investigate in depth the process of educational change that is experimented in the institution: one on LC usability and two others on students and teacher’s perception about the target change process. A total of 4,708 students and 154 professors participated in this study. The methodological design was based on Mixed Methods. After the analysis, it is concluded that the target process is located by now in the implementation phase. The discussion points out the importance of diagnose an educational change phenomenon in a holistic way. Some suggestions for future studies are give

A data mining approach to guide students through the enrollment process based on academic performance

Student academic performance at universities is crucial for education management systems. Many actions and decisions are made based on it, specifically the enrollment process. During enrollment, students have to decide which courses to sign up for. This research presents the rationale behind the design of a recommender system to support the enrollment process using the students’ academic performance record. To build this system, the CRISP-DM methodology was applied to data from students of the Computer Science Department at University of Lima, Perú. One of the main contributions of this work is the use of two synthetic attributes to improve the relevance of the recommendations made. The first attribute estimates the inherent difficulty of a given course. The second attribute, named potential, is a measure of the competence of a student for a given course based on the grades obtained in relatedcourses. Data was mined using C4.5, KNN (K-nearest neighbor), Naïve Bayes, Bagging and Boosting, and a set of experiments was developed in order to determine the best algorithm for this application domain. Results indicate that Bagging is the best method regarding predictive accuracy. Based on these results, the “Student Performance Recommender System” (SPRS) was developed, including a learning engine. SPRS was tested with a sample group of 39 students during the enrollment process. Results showed that the system had a very good performance under real-life conditions

Kinematic of a configurable manipulator using screw theory

[EN] This paper addresses the kinematic analysis of a redundant parallel manipulator with a configurable platform equipped with two end-effectors. The closure equations of the position analysis generate a system of quadratic equations which is solved by applying the Newton-homotopy method. Subsequently, the instantaneous kinematics of the robot is solved by resorting to the theory of screws. The efficiency of the method is such that the calculation of passive joint rates of the robot is not required form the determination of the input-outputn equation of velocity of the parallel manipulator. Numerical examples are compared with the outcome of a commercial software demonstrating the approach correctness.[ES] En este trabajo se aborda el análisis cinemático de un m manipulador redundante con una plataforma configurable equipada con dos efectores finales. Las ecuaciones de clausura del análisis de posición generan un sistema de ecuaciones cuadráticas el cual se resuelve aplicando Newton-homotopía. Posteriormente, la cinemática instantánea del robot se resuelve recurriendo a la teoría de tornillos. La eficiencia del método es tal que no se requiere del cálculo de las velocidades articulares pasivas del robot para la determinación de la ecuación entrada-salida de velocidad del manipulador paralelo. Ejemplos numéricos se comparan con los resultados de un software comercial lo cual demuestra veracidad del método.Este trabajo ha sido realizado gracias al apoyo del Consejo Nacional de Ciencia y Tecnología de México, Conacyt, a través de la membresía del Dr. Jaime Gallardo–Alvarado al Sistema Nacional de Investigadores.Gallardo-Alvarado, J.; Tinajero-Campo, JH.; Sánchez-Rodríguez, Á. (2020). Cinemática de un manipulador configurable por medio de la teoría de tornillos. Revista Iberoamericana de Automática e Informática industrial. 18(1):58-67. https://doi.org/10.4995/riai.2020.12793OJS5867181Aimedee, F., Gogu, G., Dai, J. S., Bouzgarrou, C., Bouton, N., 2016. Systematization of morphing in reconfigurable mechanisms. Mechanism and Machine Theory 96, 215-224. https://doi.org/10.1016/j.mechmachtheory.2015.07.009Baron, N., Philippides, A., Rojas, N., 2018. A novel kinematically redundant planar parallel robot manipulator with full rotatability. ASME Journal of Mechanisms and Robotics 11, 1-8. https://doi.org/10.1115/1.4041698Bonev, I. A., Zlatanov, D., Gosselin, C. M., 2001. Singularity analysis of 3- dof planar parallel mechanisms via screw theory. ASME Journal of Mechanical Design 125, 573-581. https://doi.org/10.1115/1.1582878Carbonari, L., Callegari, M., Palmieri, G., Palpacelli, M. C., 2014. A new class of reconfigurable parallel kinematic machines. Mechanism and Machine Theory 79, 173-183. https://doi.org/10.1016/j.mechmachtheory.2014.04.011Chakarov, D., 2004. Study of the antagonistic stiffness of parallel manipulators with actuation redundancy. Mechanism and Machine Theory 39, 583- 601. https://doi.org/10.1016/j.mechmachtheory.2003.12.001Dai, J. S., Gogu, G., 2016. Special issue on reconfigurable mechanisms: morphing, metamorphosis and reconfiguration through constraint variations and reconfigurable joints. Mechanism and Machine Theory 96, 213-214. https://doi.org/10.1016/j.mechmachtheory.2015.11.006Fang, H., Tang, T., Zhang, J., 2019. Kinematic analysis and comparison of a 2r1t redundantly actuated parallel manipulator and its non-redundantly actuated forms. Mechanism and Machine Theory 142, 1-23. https://doi.org/10.1016/j.mechmachtheory.2019.103587Gallardo-Alvarado, J., 2016. Kinematic Analysis of Parallel Manipulators by Algebraic Screw Theory. Springer International Publishing Switzerland, Switzerland. https://doi.org/10.1007/978-3-319-31126-5Gallardo-Alvarado, J., Rico-Martínez, J. M., 1998. Screw theory and helicoidal fields. Proceedings of the ASME 1998 Design Engineering Technical Conferences, ASME, cD rom.Gallardo-Alvarado, J., Rico-Martínez, J. M., 2001. Jerk influence coefficients, via screw theory, of closed chains. Meccanica 36, 213-228. https://doi.org/10.1023/A:1013074907533Gallardo-Alvarado, J., Tinajero-Campos, J. H., 2019. A parallel manipulator with planar configurable platform and three end-effectors. Mathematical Problems in Engineering Paper 7972837. https://doi.org/10.1155/2019/7972837Hoevenaars, A. G. L., Gosselin, C., Lambert, P., Herder, J. L., 2017. A systematic approach for the jacobian analysis of parallel manipulators with two end-effectors. Mechanism and Machine Theory 109, 171-194. https://doi.org/10.1016/j.mechmachtheory.2016.10.022Kang, X., Dai, J. S., 2019. Relevance and transferability for parallel mechanisms with reconfigurable platforms. ASME Journal of Mechanisms and Robotics 11, 031012 (9 pages). https://doi.org/10.1115/1.4042629Kock, S., Schumacher, W., 1998. A parallel x-y manipulator with actuation redundancy for high-speed and active-stiffness applications. IEEE International Conference on Robotics and Automation, IEEE, Leuven, pp. 2295- 2300.Kock, S., Schumacher, W., 2000. A mixed elastic and rigid-body dynamic model of an actuation redundant parallel robot with high-reduction gears. IEEE International Conference on Robotics and Automation, IEEE, San Francisco.Lambert, P., Herder, J. L., 2016. Parallel robots with configurable platforms: fundamental aspects of a new class of robotic architectures. Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, 463-472. https://doi.org/10.1177/0954406215602511Lambert, P., Herder, J. L., 2019. A 7-DOF redundantly actuated parallel haptic device combining 6-DOF manipulation and 1-DOF grasping. Mechanism and Machine Theory 134, 349-364. https://doi.org/10.1016/j.mechmachtheory.2019.01.002Landure, J., Gosselin, C., 2018. Kinematic analysis of a novel kinematically redundant spherical parallel manipulator. ASME Journal of Mechanisms and Robotics 10, 1-10. https://doi.org/10.1115/1.4038971Liu, F., Wu, J., Wang, L., Wang, J., 2014. Determination of the maxima singularity-free zone of 4-rrr redundant parallel manipulators and its application on investigating length ratios of links. Robotica 1, 1-17. https://doi.org/10.1017/S0263574714002720Ma, X., Zhang, K., Dai, J. S., 2018. Novel spherical-planar and bennett- spherical 6r metamorphic linkages with reconfigurable motion branches. Mechanism and Machine Theory 128, 628-647. https://doi.org/10.1016/j.mechmachtheory.2018.05.001Mohamed, M. G., Gosselin, C., 2005. Design and analysis of kinematically redundant parallel manipulators with configurable platforms. IEEE Transactions on Robotics 21, 277-287. https://doi.org/10.1109/TRO.2004.837234Mueller, A., 2006. Stiffness control of redundantly actuated parallel manipulators. IEEE International Conference on Robotics and Automation, IEEE, Orlando.Mueller, A., 2008. Redundant actuation of parallel manipulators. In: Wu, H. (Ed.), Parallel Manipulators, Towards New Applications. INTECH. https://doi.org/10.5772/5427Qu, H., Zhang, C., Guo, S., 2018. Structural synthesis of a class of kinematically redundant parallel manipulators based on modified G-K criterion and RDOF criterion. Mechanism and Machine Theory 130, 47- 70. https://doi.org/10.1016/j.mechmachtheory.2018.08.008Schreiber, L. T., Gosselin, C., 2018. Kinematically redundant planar parallel mechanisms: Kinematics, workspace and trajectory planning. Mechanism and Machine Theory 119, 91-105. https://doi.org/10.1016/j.mechmachtheory.2017.08.022Verschelde, J., 1999. Algorithm 795: Phcpack: a general-purpose solver for polynomial systems by homotopy continuation. ACM Transactions on Mathematical Software 25, 251-276. https://doi.org/10.1145/317275.317286Wu, T.-M., 2005. A study of convergence on the newton-homotopy continuation method. Applied Mathematics and Computation 168, 1169- 174". https://doi.org/10.1016/j.amc.2003.10.068Wu, T. manipulator -M., 2006. The inverse kinematics problem of spatial 4p3r robot by the homotopy continuation method with an adjustable auxiliary homotopy function. Nonlinear Analysis 64, 2373-2380. https://doi.org/10.1016/j.na.2005.08.021Ye, W., Fang, Y., Zhang, K., Guo, S., 2014. A new family of reconfigurable parallel mechanisms with diamond kinematotropic chain. Mechanism and Machine Theory 74, 1-9. https://doi.org/10.1016/j.mechmachtheory.2013.11.011Yi, B.-J., Na, H. Y., Lee, J. H., Hong, Y.-S., Oh, S.-R., Suh, I.-H., Kim, W. K., 2002. Design of a parallel-type gripper mechanism. International Journal of Robotics Research 21, 661-676. https://doi.org/10.1177/027836402322023240Yi, B. Y., Freeman, R. A., Tesar, D., 1994. Force and stiffness transmision in redundantly actuated mechanisms: the case for a spherical shoulder mechanism. Robotics, Spatial Mechanisma and Mechanical Systems 45, 163-172.Zhang, K., Dai, J. S., Fang, Y., 2013. Geometric constraint and mobility variation of two 3svpsv metamorphic parallel mechanisms. ASME Journal of Mechanical Design 135, paper 011001. https://doi.org/10.1115/1.400792

La cultura del bienestar: un eje esencial en las instituciones de educación superior

Workplace well-being in an organization has become an issue of great importance since it contributes to the satisfaction and motivation of workers, which in turn translates into greater productivity and profitability for the company or institution, while the opposite affects the overall performance of the organization. The objective of this study is to identify the level of well-being and quality of life of the administrative staff and teachers of the Catholic University of Cuenca, La Troncal Campus, to promote the improvement of the work environment. This research adopted a quantitative approach with a descriptive and non-experimental scope and information was collected by applying surveys to the 64 officials of this University Campus. Among the most relevant results, it was evident that a low percentage of the sample is demotivated due to work overload and dissatisfied with the work environment, alluding to the fact that the coexistence events do not meet their objectives. These findings do not indicate that the institution has a major problem; Since these difficulties can be reduced or eliminated with the implementation of new activities and measures designed for the well-being of officials.El bienestar laboral en una organización se ha vuelto un tema de gran importancia ya que contribuye a la satisfacción y motivación de los trabajadores, lo que a su vez se traduce en una mayor productividad y rentabilidad para la empresa o institución, siendo lo contrario, afecta el desempeño general de la organización. El objetivo de este estudio consiste en identificar el nivel de bienestar y la calidad de vida del personal administrativo y docentes de la Universidad Católica de Cuenca, Campus La Troncal, para promover el mejoramiento del ambiente laboral. Esta investigación adoptó un enfoque cuantitativo con alcance descriptivo y de tipo no experimental y se recopilo información mediante la aplicación de encuestas a los 64 funcionarios de este Campus Universitario. Entre los resultados más relevantes se pudo evidenciar que un bajo porcentaje de la muestra se encuentra desmotivado debido a la sobrecarga de trabajo e insatisfecho con el clima laboral, aludiendo a que los eventos de convivencia no cumplen sus objetivos. Estos hallazgos no indican que la institución presente un gran problema; puesto que, estas dificultades se pueden disminuir o eliminar con la implementación de nuevas actividades y medidas pensadas en el bienestar de los funcionarios

Secretory carcinoma of the breast containing the ETV6-NTRK3 fusion gene in a male: case report and review of the literature

BACKGROUND: Secretory carcinoma (SC) of the breast is a rare and indolent tumor. Although originally described in children, it is now known to occur in adults of both sexes. Recently, the tumor was associated with the ETV6-NTRK3 gene translocation. CASE PRESENTATION: A 52-year-old male was diagnosed with secretory breast carcinoma and underwent a modified radical mastectomy. At 18 months the tumor recurred at the chest wall and the patient developed lung metastases. He was treated concurrently with radiation and chemotherapy without response. His tumor showed the ETV6-NTRK3 translocation as demonstrated by fluorescent in situ hybridization (FISH). CONCLUSION: SC is a rare slow-growing tumor best treated surgically. There are insufficient data to support the use of adjuvant radiation or chemotherapy. Its association with the ETV6-NTRK3 fusion gene gives some clues for the better understanding of this neoplasm and eventually, the development of specific therapies